Directives

no-referrer

The Referer header will be omitted entirely. No referrer information is sent along with requests.

no-referrer-when-downgrade (default)

This is the user agent's default behavior if no policy is specified. The origin is sent as a referrer when the protocol security level stays the same (HTTPS->HTTPS), but isn't sent to a less secure destination (HTTPS->HTTP).

origin

Only send the origin of the document as the referrer in all cases.
The document https://example.com/page.html will send the referrer https://example.com/.

origin-when-cross-origin

Send a full URL when performing a same-origin request, but only send the origin of the document for other cases.

same-origin

A referrer will be sent for same-site origins, but cross-origin requests will contain no referrer information.

strict-origin

Only send the origin of the document as the referrer to a-priori as-much-secure destination (HTTPS->HTTPS), but don't send it to a less secure destination (HTTPS->HTTP).

strict-origin-when-cross-origin

Send a full URL when performing a same-origin request, only send the origin of the document to a-priori as-much-secure destination (HTTPS->HTTPS), and send no header to a less secure destination (HTTPS->HTTP).

unsafe-url

Send a full URL when performing a same-origin or cross-origin request.

This policy will leak origins and paths from TLS-protected resources to insecure origins. Carefully consider the impact of this setting.